[En-Nut-Discussion] stm32_can.c fails to build

[Uwe Bonnes]

>>>>> "Harald" == Harald Kipp <harald.kipp at egnite.de> writes:

    Harald> I got the following problem when trying to build Nut/OS for
    Harald> STM32:
    Harald> ------------------------------------------------------------------------
    Harald> Target : stm32_can-cm3-gcc-bld Command: SET
    Harald> PATH=e:\ethernut\nut-trunk\nut\tools\win32;%ProgramFiles(x86)%\yagarto\bin;e:\apps\bin;%SystemRoot%\system32;%SystemRoot%;%SystemRoot%\System32\Wbem;&make
    Harald> clean all install Error : 2
    Harald> ------------------------------------------------------------------------
    Harald> " [CC] ../.././nut/arch/cm3/dev/stm/stm32_can.c"
    Harald> ../.././nut/arch/cm3/dev/stm/stm32_can.c: In function
    Harald> 'StmCanSendMsg': ../.././nut/arch/cm3/dev/stm/stm32_can.c:867:5:
    Harald> error: dereferencing type-punned pointer will break
    Harald> strict-aliasing rules [-Werror=strict-aliasing]
    Harald> ../.././nut/arch/cm3/dev/stm/stm32_can.c: In function
    Harald> 'CanInput': ../.././nut/arch/cm3/dev/stm/stm32_can.c:941:5:
    Harald> error: dereferencing type-punned pointer will break
    Harald> strict-aliasing rules [-Werror=strict-aliasing] cc1.exe: all
    Harald> warnings being treated as errors

The trouble case is, where 4 consequitive bytes of the can frame data
payload get mapped to a 32-bit register. The cast worked for me and my gcc ;-)

Should I write as
 reg32 = byte[0] | (byte[1] <<8)| (bute[2]<<16) | (byte[3] <<24)

or is there a better construct?

Thanks

-- 
Uwe Bonnes                bon at elektron.ikp.physik.tu-darmstadt.de

Institut fuer Kernphysik  Schlossgartenstrasse 9  64289 Darmstadt
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